1. Field of the Invention
This invention relates to apparatus for controlling a voltage regulator and more particularly to a novel and highly effective "man-machine interface" that enables a user of the apparatus easily and efficiently to display and control selected parameters of the voltage regulator.
2. Description of the Prior Art
In conventional practice, the parameters of a voltage regulator are accessed by means of physical switch settings, both for viewing and for configuration. Some control systems employ numerical identification codes entered by a keypad for the purpose of viewing and modifying system parameters. These conventional mechanisms are limited in the number of physical parameters available for access because of physical space restrictions and often require a chart or index list that must be consulted by an operator in order to access the parameters.
Operation of a keyboard or other interfacing device for data input should be efficient, easy, and even to a degree intuitive. Though often criticized as less than perfect, the QWERTY layout of a conventional typewriter keyboard, for example, is preferred by most users to an alphabetical layout (ABC . . .) in part because the former places the "E" key and other relatively frequently used keys in positions that are more accessible than, for example, that of the "Q" key and other relatively infrequently used keys.
It has been found that interfaces developed heretofore for permitting access to various parameters of voltage regulators are very awkward to use.
Representative prior art relating to menus, user interfaces, and keypads is found in U.S. Pat. Nos. 361,730, 4,503,291, 4,628,158, 4,645,874 and 5,077,582. The apparatus and techniques disclosed in these patents are representative of the current state of the art in this field; they do not enable an operator of a voltage regulator control to gain access to system parameters for viewing and modification with great ease and efficiency.